姓名 学号 学院 专业 座位号 ( 密 封 线 内 不 答 题 )密封线线_ _ 诚信应考,考试作弊将带来严重后果！ 华南理工大学期末考试大学物理2011-2012(2) 期末试卷（B卷）注意事项：1. 考前请将密封线内各项信息填写清楚； 2. 所有答案请直接答在答题纸上； 3考试形式：闭卷； 4. 本试卷共15题，满分100分，考试时间120分钟。考试时间：2012年7月2日9：00-11：00题 号12345678得 分评卷人题 号9101112131415总分得 分评卷人Completion (Total 40 points, 4 points/question)1. A particle leaves the origin with an initial velocity and a constant acceleration . When it reaches its maximum coordinate, its velocity is .2. A force acts on a particle as the particle moves along an axis, with in newtons, in meters, and a constant. At , the particles kinetic energy is 20.0 J; at , it is 11.0 J. Find 4.00 N/m .3. The figure shows a particle moving in a horizontal circle. A force acts on the particle. During the particle moving from point to (0，2R), the work done by is . 4. A 4.0 kg bundle starts up a 30o incline with 128 J of kinetic energy. If the coefficient of kinetic friction between bundle and incline is 0.30, it will slide up the incline 4.3 m.5. The angular acceleration of a wheel is , with in radians per second-squared and in seconds. At time , the wheel has an angular velocity of and an angular position of . Write expressions for (a) the angular velocity (rad/s) ;(b) the angular position (rad).Fig. B-2Fig. B-2Fig. B-26. An iron anchor of density 7870 kg/m3 appears 200 N lighter in water than in air. The volume of the anchor is . Its weight in the air is .7. In the figure, two diverse springs of spring constant respectively and are in series attached to a block of mass , the frequency of oscillation is .8. A stationary motion detector sends sound waves of frequency 0.150 MHz toward a truck approaching at a speed of 45.0 m/s. The frequency of the waves reflected back to the detector is 0.195 MHz .pVadbc9. The figure represents a closed cycle for a gas (the figure is not drawn to scale). The change in the internal energy of the gas as it moves from a to c along the path abc is -200 J. As it moves from c to d, 180 J must be transferred to it as heat. An additional transfer of 80 J to it as heat is needed as it moves from d to a. As it moves from c to d, the work done on the gas is 60 J .10. The figure shows the Maxwell-Boltzmann velocity distribution functions of a gas for two different temperatures and , then (, or = ). Calculation (Total 60 points)11(Total 12 points, 6 points/question) A person of mass = 32.5 kg on ice disdainfully throws a quantum text book weighing = 2.25 kg at = 12 m/s. The book is thrown from zero height and the total distance between the book and the offender is 15.2 m when the book lands. (1) At what angle was this excellent book thrown?(2) How fast is the offender moving?Solution:(1) Since there are no external forces in the horizontal direction on the person-book system, the component of the center of mass does not move while the book is in the air. We can use this fact to find how far the book travels before it hits the ground.Where is the total final separation of the book and the person. Plugging in numbers, . Take the book to be thrown at an angle with respect to the horizontal. Then the books initial velocity in the direction is and that in the direction is . In the direction we know that.In the direction, the book starts and ends the same height so, Substitute , we find.(2) Taking the persons final velocity to be , we know from conservation of momentum thatwe find . Answer: (1) the book is thrown at angle ; (2) the offender has a final velocity of . (Note: because of the double angle formula, for , there is a second solution when the angle is equal to ).12. (Total 12 points, 4 points/question) (1) What is the rotational inertia of a propeller with three blades (treated as rods) of mass , length at 120o relative to each other?(2) If a torque acts on this propeller, how long will it take to reach an angular velocity ?(3) How many revolutions will it have made before reaching this ?Solution(1) We know that the rotational inertia of a single rod rotating around its end is . Its not hard to convince oneself that if there are three of them rotating around the same axis and in the same plane, the rotational inertia is just three times this, .(2) Since and ,.(3) From our knowledge of constant acceleration problems,The number of revolution it made is13(Total 12 points) A hollow spherical iron shell floats almost completely submerged in water. The outer diameter is 60.0 cm, and the dens